In this example, we use the default, no-args GridLayout() constructor to create a layout with a single column.

public class SingleColumnGridLayoutExample {

    private final Display display;
    private final Shell shell;

    public SingleColumnGridLayoutExample() {
        display = new Display();
        shell = new Shell(display);

        // Create the layout and apply to the Shell
        shell.setLayout(new GridLayout());

        // Add the child controls to the Shell - in this case, in a single column
        final Button buttonA = new Button(shell, SWT.PUSH);
        buttonA.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonA.setText("Button A");

        final Button buttonB = new Button(shell, SWT.PUSH);
        buttonB.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonB.setText("Button B");

        final Button buttonC = new Button(shell, SWT.PUSH);
        buttonC.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonC.setText("Button C");

        final Button buttonD = new Button(shell, SWT.PUSH);
        buttonD.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonD.setText("Button D");
    }

    public void run() {
        shell.pack();
        shell.open();

        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }

    public static void main(final String... args) {
        new SingleColumnGridLayoutExample().run();
    }

}

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Similar to the Single-Column Example above, if we instead use the GridLayout(int, boolean) constructor, we can create a layout with multiple columns.

In this case we create two columns, each of which are the same width.

public class MultiColumnGridLayoutExample {

    private final Display display;
    private final Shell shell;

    public MultiColumnGridLayoutExample() {
        display = new Display();
        shell = new Shell(display);

        // Create the layout and apply to the Shell
        shell.setLayout(new GridLayout(2, true));

        // Add the child controls to the Shell - in this case, in two columns
        final Button buttonA = new Button(shell, SWT.PUSH);
        buttonA.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonA.setText("Button A");
        
        final Button buttonB = new Button(shell, SWT.PUSH);
        buttonB.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonB.setText("Button B");
        
        final Button buttonC = new Button(shell, SWT.PUSH);
        buttonC.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonC.setText("Button C");
        
        final Button buttonD = new Button(shell, SWT.PUSH);
        buttonD.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonD.setText("Button D");
    }

    public void run() {
        shell.pack();
        shell.open();

        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }

    public static void main(final String... args) {
        new MultiColumnGridLayoutExample().run();
    }

}

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By leveraging some of the member variables in the GridLayout instance, we can change the margins around the layout, and spacing between cells. In this example we set the following:

1. verticalSpacing = 0 - Sets the vertical spacing between cells to 0px.
2. horizontalSpacing = 20 - Sets the horizontal spacing between cells to 20px.
3. marginWidth = 10 - Sets the left and right margins of the layout to 10px.

Note: We do not modify the marginHeight, so it stays at the default 5px.

public class GridLayoutExample {

    private final Display display;
    private final Shell shell;

    public GridLayoutExample() {
        display = new Display();
        shell = new Shell(display);

        // Create a layout with two columns of equal width
        final GridLayout shellLayout = new GridLayout(2, true);
        shellLayout.verticalSpacing = 0; // Vertical spacing between cells
        shellLayout.horizontalSpacing = 20; // Horizontal spacing between cells
        shellLayout.marginWidth = 10; // Horizontal margin around the layout
        shell.setLayout(shellLayout);

        final Button buttonA = new Button(shell, SWT.PUSH);
        buttonA.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonA.setText("Button A");

        final Button buttonB = new Button(shell, SWT.PUSH);
        buttonB.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonB.setText("Button B");

        final Button buttonC = new Button(shell, SWT.PUSH);
        buttonC.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonC.setText("Button C");

        final Button buttonD = new Button(shell, SWT.PUSH);
        buttonD.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        buttonD.setText("Button D");
    }

    public void run() {
        shell.pack();
        shell.open();

        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }

    public static void main(final String... args) {
        new GridLayoutExample().run();
    }

}

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